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Ectodermal Organ Development Is Regulated by amicroRNA-26b-Lef-1-WntSignaling Axis
Journal article   Open access   Peer reviewed

Ectodermal Organ Development Is Regulated by amicroRNA-26b-Lef-1-WntSignaling Axis

Steve Eliason, Thad Sharp, Mason Sweat, Yan Y. Sweat and Brad A. Amendt
Frontiers in physiology, Vol.11, 780
07/14/2020
DOI: 10.3389/fphys.2020.00780
PMCID: PMC7372039
PMID: 32760291
url
https://doi.org/10.3389/fphys.2020.00780View
Published (Version of record) Open Access

Abstract

The developmental role ofLef-1in ectodermal organs has been characterized usingLef-1murine knockout models. We generated aLef-1conditional over-expression (COEL) mouse to determine the role ofLef-1expression in epithelial structures at later stages of development after endogenous expression switches to the mesenchyme.Lef-1over expression (OE) in the oral epithelium creates a new dental epithelial stem cell niche that significantly increases incisor growth. These data indicate thatLef-1expression is switched off in the dental epithelial at early stages to maintain the stem cell niche and regulate incisor growth. Bioinformatics analyses indicated thatmiR-26bexpression increased coinciding with decreasedLef-1expression in the dental epithelium. We generated a murine model over-expressingmiR-26bthat targets endogenousLef-1expression andLef-1-related developmental mechanisms.miR-26bOE mice have ectodermal organ defects including a lack of incisors, molars, and hair similar to theLef-1null mice.miR-26bOE rescues theLef-1OE phenotype demonstrating a critical genetic and developmental role formiR-26bin the temporal and spatial expression ofLef-1in epithelial tissues.Lef-1expression regulates Wnt signaling and Wnt target genes as well as cell proliferation mechanisms, whilemiR-26bOE reduced the levels of Wnt target gene expression. The extra stem cell compartment in theCOELmice expressedLef-1suggesting thatLef-1is a stem cell factor, which was absent in themiR-26b OE/COELrescue mice. This is the first demonstration of a microRNA OE mouse model that has ectodermal organ defects. These findings demonstrate that the levels ofLef-1are critical for development and establish a role formiR-26bin the regulation of ectodermal organ development through the control ofLef-1expression and an endogenous stem cell niche.
Physiology Life Sciences & Biomedicine Science & Technology

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